1. Field of the invention
The present invention relates to a data encoder for generating data groups to be recorded by the recording system to record the data in the predetermined format on a recording medium such as a magneto-optic disc.
2. Description of Related Art
A variety of digital data recording media have been put into practical use in these years with inclusion of well known systems, for example, a reproduction-only system utilizing an optical disc such as a compact disc system and a minidisc system allowing users to record/reproduce the audio data on a recording medium such as a magneto-optic disc.
In a minidisc system, the recording operation to a magneto-optic disc is performed in units of clusters. That is, a cluster is the minimum unit for the recording operation.
As shown in FIGS. 6a and 6b, one cluster is composed of 36 sectors. The 32 sectors from $00 to $1F among these sectors are defined as the main data sectors to record actual audio data and administration information. The remaining four sectors from $FC to $FF are defined as the subdata sectors.
The recording operation in units of cluster is started from the center of the sector $FD in the linking region and the data is recorded in the 32 sectors from $00 to $1F.
The main data sectors $00 to $1F respectively have a sector format as shown in FIG. 6c. One sector is composed of 2352 bytes from the byte 0 to the byte 2351. The predetermined data is recorded as the synchronization pattern in the first 12 bytes from the byte 0 to the byte 11.
Next, the bytes 12 and 13 are defined as the cluster address and the byte 14, as the sector address. As explained above, an address is recorded in each sector using three bytes. Continuously, mode data is recorded with one byte of the byte 15. The four bytes from the byte 12 to the byte 15 are defined as a header of each sector.
Moreover, the four bytes from the byte 16 to the byte 19 are defined as a subheader and these bytes are actually used for recording of zero (Null) data.
Following the subheader, the 2332 bytes from from the byte 20 to the byte 2351 are defined as a data area to be actually used for the recording of audio data and administration information.
The subdata sector from the sector $FC to sector $FF which is called as the linking region has the same sector format as the main data sector. However, in the subdata sector, the 2332 bytes forming a data area from the byte 20 to the byte 2351 are all used for recording of zero (Null) data as the dummy data as shown in FIG. 6d.
When audio data is inputted for the recording in a minidisc system, such audio data is once compressed and thereafter is sequentially fetched into a buffer RAM in data amount units each corresponding to one sector. The data is then sequentially read from the buffer RAM to form a data stream of the sector format with the addition of a synchronization pattern, a cluster address, a sector address, mode data and a subheader as shown in FIG. 6.
Sector data thus generated undergoes Advanced Cross Interleaved Reed Solomon Code (ACIRC) and Eight to Fourteen Modulation (EFM) encoding and is then supplied to a recording head for the recording into a magneto-optic disc.
Here, in view of generating sector data obtained by adding the synchronization pattern, etc. to the main data such as audio data, a microcomputer provided for controlling the recording operation has transmitted a command for setting the cluster and sector address in each transfer timing of sector data.
Moreover, the main data area is designated by the Null data in the subdata sector as explained above and therefore the microcomputer has issued also a command to give the Null data to the data area for generation of such subdata sector.
In addition, such control must be performed before the sector data is transferred for the ACIRC and EFM encoding and therefore the microcomputer always has to administrate the information about one preceding sector.
As a result, here lies a problem that a processing load to be shared on the microcomputer increases remarkably with occasional occurrence of an additional problem in generation of wrong setting of the sector address.